1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copying machine, facsimile, printer, or the like, and an image carrier unit used therein.
2. Description of the Related Art
Color is becoming more common in this type of image forming apparatus, in response to market requirements. One example is the widely used so-called tandem type image forming apparatus. In the tandem type image forming apparatus, a plurality of photosensitive members as image carriers and toner image forming means for forming toner images on the photosensitive members are provided and arranged Single color toner images formed on each photosensitive member are successively transferred and superimposed to form a color image. Also, tandem type image forming apparatus in which frames are provided for the plurality of photosensitive members, either individually or integrated with the toner image forming means, to form a plurality of photosensitive member units, are widely used. In this way the plurality of photosensitive member units can be removed from the main body of the image forming apparatus via the frames. Therefore, the photosensitive members and toner image forming means can be easily replaced in accordance with their life.
Also, Japanese Patent Application Laid-open No. 2000-293044 discloses a system that uses an intermediate transfer member, such as an intermediate transfer belt, as a transfer system used in the tandem type image forming apparatus. In this transfer system, toner images formed on the photosensitive members are transferred and superimposed onto the surface of a moving intermediate transfer belt in a primary transfer operation. Then the superimposed toner image is transferred onto the recording medium from the intermediate transfer belt in a secondary transfer operation. Also, intermediate transfer member cleaning means is provided for removing secondary transfer residual toner from the intermediate transfer belt after the secondary transfer of the superimposed image on the intermediate transfer belt to the recording medium, so that the next image forming operation is not affected.
The intermediate transfer belt and the intermediate transfer cleaning means must be replaced in accordance with their life, so they are designed to be removable from the main body of the image forming apparatus. However, the replacement procedure is complex for image forming apparatus that is structured so that both the intermediate transfer belt and the intermediate transfer cleaning means are individually removed for replacement. Therefore, when either the intermediate transfer belt or the intermediate transfer cleaning means are to be replaced, normally a special serviceperson carries out the operation. By calling on a service person to carry out all the replacements, a personnel cost is incurred every time a call is made, which results in increasing the replacement cost. Also, users that do not call on a service person but carry out the replacement themselves, must individually remove the parts when both the intermediate transfer belt and the intermediate transfer cleaning means are changed, and this leads to an increased operational burden.
On the other hand, as shown in Japanese Patent Application Laid-open No. 2005-181820, the replacement procedure is simplified by changing the intermediate transfer belt and the intermediate transfer member cleaning means as a unit, so an ordinary user can carry out the replacement. However, the life of the intermediate transfer cleaning means is significantly shorter compared with the intermediate transfer belt, and must be changed more frequently. Therefore if the intermediate transfer belt is replaced in accordance with the shorter life of the intermediate transfer cleaning member means, the problem of waste of components and poor cost performance arises.